body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  font-family: var(--font-sans);
  color: var(--color-text-primary);
  background: var(--color-surface-secondary);
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--color-text-primary);
  text-decoration: none;
}

a:hover {
  color: var(--color-primary);
}

/* Links inside page content are blue; nav and brand links stay ink */
main a {
  color: var(--color-primary);
}

main a:hover {
  text-decoration: underline;
}

textarea,
select,
button {
  font: inherit;
  color: inherit;
}

a,
.btn {
  transition: color var(--transition-fast), border-color var(--transition-fast);
}

a:focus-visible,
select:focus-visible,
.btn:focus-visible,
.toggle-input:focus-visible + .toggle-switch {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

/* The card clips overflow, so the ring sits inside the pane */
.text:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: -2px;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
  border: 0;
}

.shell {
  box-sizing: border-box;
  width: 100%;
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 var(--spacing-8);
}

.nav {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
}

.nav .shell,
.foot .shell {
  height: 56px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--spacing-4);
}

.brand {
  display: flex;
  align-items: center;
  gap: var(--spacing-2);
  font-size: var(--text-base);
  font-weight: 700;
}

.brand svg {
  width: 26px;
  height: 26px;
  fill: currentColor;
  flex-shrink: 0;
}

.links {
  display: flex;
  align-items: center;
  gap: var(--spacing-6);
  font-size: var(--text-base);
  font-weight: 500;
}

.select {
  height: 32px;
  /* The right side reserves room for the native arrow */
  padding: 0 var(--spacing-6) 0 var(--spacing-3);
  font-size: var(--text-base);
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
}

main {
  flex-grow: 1;
}

main .shell {
  padding-top: var(--spacing-12);
  padding-bottom: var(--spacing-10);
  display: flex;
  flex-direction: column;
  gap: var(--spacing-8);
}

.hero {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-2);
}

.hero h1 {
  margin: 0;
  font-size: var(--text-3xl);
  font-weight: 600;
  line-height: 1.2;
}

.hero p {
  margin: 0;
  font-size: var(--text-lg);
  line-height: 1.5;
  color: var(--color-text-secondary);
  text-wrap: pretty;
}

.tool {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-3);
}

.card {
  display: flex;
  flex-direction: column;
  overflow: hidden;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
}

.toolbar {
  display: flex;
  align-items: center;
  gap: var(--spacing-6);
  padding: var(--spacing-3) var(--spacing-4);
  border-bottom: 1px solid var(--color-border);
}

.toggle {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-2);
  cursor: pointer;
}

.toggle.end {
  margin-left: auto;
}

.toggle:has(:disabled) {
  cursor: not-allowed;
}

.toggle-label {
  font-size: var(--text-base);
  font-weight: 500;
}

.toggle:has(:disabled) .toggle-label {
  color: var(--color-text-secondary);
}

.toggle-switch {
  position: relative;
  width: 44px;
  height: 24px;
  flex-shrink: 0;
  background: var(--color-surface-tertiary);
  border-radius: var(--radius-full);
  box-shadow: inset 0 0 0 1px var(--color-border);
  transition: background-color var(--transition), box-shadow var(--transition);
}

.toggle-switch::after {
  content: "";
  position: absolute;
  top: 2px;
  left: 2px;
  width: 20px;
  height: 20px;
  background: var(--color-surface);
  border-radius: var(--radius-full);
  box-shadow: var(--shadow);
  transition: background-color var(--transition), transform var(--transition);
}

.toggle-input:checked + .toggle-switch {
  background: var(--color-primary-light);
  box-shadow: none;
}

.toggle-input:checked + .toggle-switch::after {
  background: var(--color-primary);
  transform: translateX(20px);
}

.toggle-input:disabled + .toggle-switch {
  box-shadow: none;
}

.panes {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  min-height: 380px;
}

.pane {
  display: flex;
  flex-direction: column;
}

.pane.left {
  border-right: 1px solid var(--color-border);
}

.pane-head {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--spacing-3);
  height: 40px;
  padding: 0 var(--spacing-2) 0 var(--spacing-4);
  border-bottom: 1px solid var(--color-border-light);
  font-size: var(--text-base);
  font-weight: 600;
  color: var(--color-text-secondary);
}

.pane-status {
  margin-left: auto;
  font-weight: 400;
  white-space: nowrap;
}

.pane-status.asking::after {
  content: "…";
  animation: blink 1.2s steps(2, jump-none) infinite;
}

.pane-status.done {
  color: var(--color-success);
}

/* Sits on the pane head's bottom border, so it takes no room */
.pane-bar {
  position: absolute;
  left: 0;
  right: 0;
  bottom: -1px;
  height: 2px;
  overflow: hidden;
  background: var(--color-primary-light);
}

.pane-bar::after {
  content: "";
  position: absolute;
  top: 0;
  bottom: 0;
  width: 40%;
  background: var(--color-primary);
  animation: sweep 1.4s cubic-bezier(0.4, 0, 0.2, 1) infinite;
}

@keyframes blink {
  to {
    opacity: 0.2;
  }
}

@keyframes sweep {
  from {
    left: -40%;
  }
  to {
    left: 100%;
  }
}

.btn {
  height: 32px;
  padding: 0 var(--spacing-3);
  font-size: var(--text-base);
  font-weight: 500;
  color: var(--color-text-primary);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  cursor: pointer;
}

.btn:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

/* The main action of a page. Measurements match the pangu.js extension's .btn-primary */
.btn-primary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-2);
  height: auto;
  padding: var(--spacing-3) var(--spacing-6);
  font-size: var(--text-base);
  line-height: 1.25rem;
  white-space: nowrap;
  color: var(--color-text-on-primary);
  background: var(--color-text-primary);
  border-color: var(--color-text-primary);
  border-radius: var(--radius);
  transition: opacity var(--transition-fast);
}

.btn-primary:hover:not(:disabled) {
  color: var(--color-text-on-primary);
  border-color: var(--color-text-primary);
  opacity: 0.9;
}

.btn-primary:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

/* Both labels share one cell, so the button keeps the width of the longer one */
.btn-copy {
  display: inline-grid;
  align-items: center;
  justify-items: center;
}

.btn-copy span {
  grid-area: 1 / 1;
  transition: opacity var(--transition-fast);
}

.btn-copy .when-copied,
.btn-copy.copied .when-idle {
  opacity: 0;
}

.btn-copy.copied .when-copied {
  opacity: 1;
}

.text {
  flex-grow: 1;
  box-sizing: border-box;
  width: 100%;
  margin: 0;
  padding: var(--spacing-4);
  font-size: var(--text-base);
  line-height: 1.8;
  border: 0;
  background: transparent;
  resize: none;
  white-space: pre;
  overflow-x: auto;
  /* Grows with its content, so both panes stay line for line */
  field-sizing: content;
}

.text::placeholder {
  color: var(--color-text-tertiary);
}

.diff {
  flex-grow: 1;
  display: flex;
  flex-direction: column;
  padding: var(--spacing-4) 0;
  font-size: var(--text-base);
  line-height: 1.8;
  overflow-x: auto;
}

.row {
  width: max-content;
  min-width: 100%;
  /* An empty line keeps its height */
  min-height: 1.8em;
  box-sizing: border-box;
  padding: 0 var(--spacing-4);
  white-space: pre;
}

.row.add {
  background: var(--color-diff-row-add);
}

.row.del {
  background: var(--color-diff-row-del);
}

.row.mix {
  background: var(--color-diff-row-mix);
}

.a,
.d {
  border-radius: 2px;
}

.a {
  background: var(--color-diff-add);
}

/* An empty inline box keeps the text's height, like .a. The negative margin cancels its 2px width */
.d {
  padding: 0 1px;
  margin: 0 -1px;
  background: var(--color-diff-del);
}

.strip {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  /* A fixed row: it keeps this height with the legend hidden */
  box-sizing: border-box;
  min-height: 48px;
  padding: 0 var(--spacing-4);
  border-top: 1px solid var(--color-border);
  background: var(--color-surface-secondary);
}

.strip-status {
  margin: 0;
  font-size: var(--text-base);
  line-height: 1.5;
  color: var(--color-info);
}

.strip-status.danger {
  color: var(--color-danger);
}

.legend {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: var(--spacing-3);
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
}

.legend span {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-2);
}

.legend i {
  width: 12px;
  height: 12px;
}

.note {
  /* Adds to the container's gap, for 24px above the note */
  margin: var(--spacing-3) 0 0;
  text-align: center;
  font-size: var(--text-base);
  line-height: 1.5;
  color: var(--color-text-secondary);
}

.foot {
  border-top: 1px solid var(--color-border);
  font-size: var(--text-base);
  color: var(--color-text-secondary);
}

.foot nav {
  display: flex;
  gap: var(--spacing-2);
}

/* Footer links: ink with a light underline, blue on hover */
.foot a {
  color: var(--color-text-primary);
  text-decoration: underline;
  text-decoration-color: var(--color-text-tertiary);
  text-decoration-color: color-mix(in srgb, var(--color-text-tertiary) 50%, var(--color-border));
}

.foot a:hover {
  color: var(--color-primary);
  text-decoration-color: currentColor;
}

.foot i {
  font-style: normal;
  color: var(--color-text-tertiary);
}

.hscroll::-webkit-scrollbar {
  height: 8px;
}

.hscroll::-webkit-scrollbar-thumb {
  background: var(--color-border);
  border-radius: 4px;
}

[hidden] {
  display: none !important;
}

@media (max-width: 640px) {
  .shell {
    padding: 0 var(--spacing-4);
  }

  .nav .shell {
    height: 52px;
  }

  .brand svg {
    width: 24px;
    height: 24px;
  }

  .links {
    gap: var(--spacing-3);
  }

  .links .select {
    padding: 0 var(--spacing-6) 0 var(--spacing-2);
  }

  /* The footer keeps the GitHub link, and the Chinese language name needs the room */
  .links .wide-only {
    display: none;
  }

  main .shell {
    padding-top: var(--spacing-8);
    padding-bottom: var(--spacing-8);
    gap: var(--spacing-6);
  }

  .hero h1 {
    font-size: var(--text-2xl);
  }

  .toolbar {
    flex-wrap: wrap;
    gap: var(--spacing-1) var(--spacing-6);
    padding: var(--spacing-2) var(--spacing-4);
  }

  .toolbar .select {
    flex-basis: 100%;
    width: 100%;
    height: 40px;
  }

  .toggle {
    min-height: 44px;
  }

  .panes {
    grid-template-columns: minmax(0, 1fr);
    min-height: 0;
  }

  .pane.left {
    border-right: 0;
    border-bottom: 1px solid var(--color-border);
  }

  .pane .text,
  .pane .diff {
    min-height: 262px;
  }

  .pane-head {
    height: 44px;
  }

  .btn {
    height: 36px;
  }

  .strip {
    justify-content: flex-start;
    flex-wrap: wrap;
    gap: var(--spacing-1) var(--spacing-6);
    padding: var(--spacing-2) var(--spacing-4);
  }

  .legend {
    margin-left: 0;
  }

  .foot .shell {
    height: auto;
    padding: var(--spacing-5) var(--spacing-4);
    flex-wrap: wrap;
    gap: var(--spacing-3) var(--spacing-4);
  }

  .foot nav {
    flex-wrap: wrap;
    justify-content: flex-end;
    margin-left: auto;
  }
}

/* * alone does not match pseudo-elements, and the toggle knob is an ::after */
@media (prefers-reduced-motion: reduce) {
  *,
  ::before,
  ::after {
    transition: none !important;
    animation: none !important;
  }

  /* A still line stands in for the sweep */
  .pane-bar::after {
    left: 0;
    width: 100%;
    opacity: 0.5;
  }
}